They said the man had also approached children at his son's school and had "protested" at the school on his son's 13th birthday.

Mrs Justice Theis also revealed that another, lower-ranking, family court judge had in October made decisions about the teenager's future care following hearings at a family court in Kent.

She said Judge Veronica Hammerton had concluded that the boy should remain in long-term foster care - and have "contact" with his father six times a year.

Judge Hammerton full ruling has yet to be made public.

Mrs Justice Theis said the boy had first been removed from his father's care in 2012. She said the youngster, then 10, had been found home alone after fire-fighters were called following a report of a fire.

Medway Council had started family court proceedings and a judge, who was told that the pianist had left the boy home alone more than once, concluded the youngster was at "risk of significant emotional and physical harm".

But the boy had been returned to his father's care in 2013 after the musician completed a "parenting course".

Mrs Justice Theis said in March this year police had called social workers.

Officers said the pianist had called an ambulance saying that the youngster was "violent" and "smashing up the house". The judge said police had "reported unsuitable home conditions".

In April, police had been called again after the pianist said the youngster had "trashed the house with a hammer" and fired air gun pellets at him.

"When the police arrived, (the boy) was noted to be hiding under a piano and was emotional when the police spoke to him," said Mrs Justice Theis.

"(The boy) reported to them the demands made on him by the father regarding extra homework, attending Russian schooling were too much.

"The officers noted when (the boy) tried to talk to the father he shouted him down.

"The officers sought to mediate; they noted the unkempt state of the home and a hole in a glass pane.

"They noted the father continued to refuse to accept he was in any part to blame for the parenting concerns regarding (the boy), insisting the full blame was on the local authority."

She said a few days later the pianist called police again.

"He reported that (the boy) was causing damage to the property, smashing items and using matches, and was threatening to set himself on fire," said Mrs Justice Theis.

"He wanted the police to discipline (the boy). He was advised to contact the local authority but he said they would not help him.

"The police attended the next morning, social services were asked to attend and a decision was taken for (the boy) to be placed in police protection. The father was arrested on suspicion of child neglect."

She said shortly afterwards the boy was placed into temporary foster care.